We investigated this issue. The issue occurred not only with the circumflex mark (^) while using German keyboard layouts, but in similar situations for other locales. For example, for the accent mark in Spanish in which letters like á and é can be entered. The problem was fixed in the v6.0.37 we have just published on the website.
On some keyboards like German or Spanish, the user may press a diacritical mark key (^, ') + letter to enter one combined letter. If the pressed diacritical mark cannot be applied to the 2nd char, the system generates two KeyPress events together between KeyDown and KeyUp for the 2nd key. For example, here is the sequence of events if you press 1, 2 on a German keyboard:
<KeyDown> KeyData=D1
<KeyPress> KeyChar=1
<KeyUp> KeyData=D1
<KeyDown> KeyData=D2
<KeyPress> KeyChar=2
<KeyUp> KeyData=D2
If you press ^+A to enter â, we get this:
<KeyDown> KeyData=Oem5
<KeyUp> KeyData=Oem5
<KeyDown> KeyData=A
<KeyPress> KeyChar=â
<KeyUp> KeyData=A
However, the situation changes if the ^ modifier is not applicable for the next symbol. Let's press ^+2:
<KeyDown> KeyData=Oem5
<KeyUp> KeyData=Oem5
<KeyDown> KeyData=D2
<KeyPress> KeyChar=^
<KeyPress> KeyChar=2
<KeyUp> KeyData=D2
iGrid is put into edit mode after the 1st KeyPress thinking its a normal sequence of events and there will be no second subsequent KeyPress. To fix the issue, we needed to implement special processing for the 2nd KeyPress and pass the 2nd character to the cell editor, keeping all iGrid specific features like the TextBoxFilterChar event. This has been successfully done in the v6.0.37.